Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
International Journal of Aeronautical and Space Sciences
Journal Basic Information
Journal DOI :
The Korean Society for Aeronautical & Space Sciences
Editor in Chief :
Volume & Issues
Volume 11, Issue 4 - Dec 2010
Volume 11, Issue 3 - Sep 2010
Volume 11, Issue 2 - Jun 2010
Volume 11, Issue 1 - Mar 2010
Selecting the target year
Numerical Simulation of Rotor-Fuselage Aerodynamic Interaction Using an Unstructured Overset Mesh Technique
Lee, Bum-Seok ; Jung, Mun-Seung ; Kwon, Oh-Joon ; Kang, Hee-Jung ;
International Journal of Aeronautical and Space Sciences, volume 11, issue 1, 2010, Pages 1~9
DOI : 10.5139/IJASS.2010.11.1.001
Numerical simulation of unsteady flows around helicopters was conducted to investigate the aerodynamic interaction of main rotor and other components such as fuselage and tail rotor. For this purpose, a three-dimensional inviscid flow solver has been developed based on unstructured meshes. An overset mesh technique was used to describe the relative motion between the main rotor, and other components. As the application of the present method, calculations were made for the rotor-fuselage aerodynamic interaction of the ROBIN (ROtor Body INteraction) configuration and for a complete UH-60 helicopter configuration consisted of main rotor, fuselage, and tail rotor. Comparison of the computational results was made with measured time-averaged and instantaneous fuselage surface pressure distributions for the ROBIN configuration and thrust distribution and available experimental data for the UH-60 configuration. It is demonstrated that the present method is efficient and robust for the simulation of complete rotorcraft configurations.
Finding Optimal Controls for Helicopter Maneuvers Using the Direct Multiple-Shooting Method
Kim, Min-Jae ; Hong, Ji-Seung ; Kim, Chang-Joo ;
International Journal of Aeronautical and Space Sciences, volume 11, issue 1, 2010, Pages 10~18
DOI : 10.5139/IJASS.2010.11.1.010
The purpose of this paper deals with direct multiple-shooting method (DMS) to resolve helicopter maneuver problems of helicopters. The maneuver problem is transformed into nonlinear problems and solved DMS technique. The DMS method is easy in handling constraints and it has large convergence radius compared to other strategies. When parameterized with piecewise constant controls, the problems become most effectively tractable because the search direction is easily estimated by solving the structured Karush-Kuhn-Tucker (KKT) system. However, generally the computation of function, gradients and Hessian matrices has considerably time-consuming for complex system such as helicopter. This study focused on the approximation of the KKT system using the matrix exponential and its integrals. The propose method is validated by solving optimal control problems for the linear system where the KKT system is exactly expressed with the matrix exponential and its integrals. The trajectory tracking problem of various maneuvers like bob up, sidestep near hovering flight speed and hurdle hop, slalom, transient turn, acceleration and deceleration are analyzed to investigate the effects of algorithmic details. The results show the matrix exponential approach to compute gradients and the Hessian matrix is most efficient among the implemented methods when combined with the mixed time integration method for the system dynamics. The analyses with the proposed method show good convergence and capability of tracking the prescribed trajectory. Therefore, it can be used to solve critical areas of helicopter flight dynamic problems.
Performance Analysis and Optimal Design of Heat Exchangers Used in High Temperature and High Pressure System
Kim, Yang-Gu ; Choi, Byoung-Ik ; Kim, Kui-Soon ; Jeong, Ji-Hwan ;
International Journal of Aeronautical and Space Sciences, volume 11, issue 1, 2010, Pages 19~25
DOI : 10.5139/IJASS.2010.11.1.019
A computational study for the optimal design of heat exchangers (HX) used in a high temperature and high pressure system is presented. Two types of air to air HX are considered in this study. One is a single-pass cross-flow type with straight plain tubes and the other is a two-pass cross-counter flow type with plain U-tubes. These two types of HX have the staggered arrangement of tubes. The design models are formulated using the number of transfer units (
-NTU method) and optimized using a genetic algorithm. In order to design compact light weight HX with the minimum pressure loss and the maximum heat exchange rate, the weight of HX core is chosen as the object function. Dimensions and tube pitch ratio of a HX are used as design variables. Demanded performance such as the pressure loss (
) and the temperature drop (
) are used as constraints. The performance of HX is discussed and their optimal designs are presented with an investigation of the effect of design variables and constraints.
Study on Comparison of Atmospheric and Vacuum Environment of Thermally-Induced Vibration Using Vacuum Chamber
Kong, Chang-Duk ; Park, Hyun-Bum ; Lee, Ha-Seaung ;
International Journal of Aeronautical and Space Sciences, volume 11, issue 1, 2010, Pages 26~30
DOI : 10.5139/IJASS.2010.11.1.026
The present paper studies the thermally-induced vibration phenomenon of the flexible space boom structure. In order to simulate the thermally-induced vibration phenomenon of the flexible thin boom structure of the spacecraft with the attached tip mass in space, the thermally-induced vibration including thermal flutter is experimentally investigated at various thermal environments using a heating lamp in vacuum chamber. In this experimental study, fluctuating characteristics, natural frequency and thermal strains of the thermally-induced vibration are parametrically investigated at various thermal environment conditions. Finally the thermally-induced vibration of the flexible boom structure of the orbiting earth satellite in solar radiation environment from the earth eclipse region including umbra and penumbra is simulated using the power control of the heating lamp in the vacuum chamber.
Motion and Structure Estimation Using Fusion of Inertial and Vision Data for Helmet Tracker
Heo, Se-Jong ; Shin, Ok-Shik ; Park, Chan-Gook ;
International Journal of Aeronautical and Space Sciences, volume 11, issue 1, 2010, Pages 31~40
DOI : 10.5139/IJASS.2010.11.1.031
For weapon cueing and Head-Mounted Display (HMD), it is essential to continuously estimate the motion of the helmet. The problem of estimating and predicting the position and orientation of the helmet is approached by fusing measurements from inertial sensors and stereo vision system. The sensor fusion approach in this paper is based on nonlinear filtering, especially expended Kalman filter(EKF). To reduce the computation time and improve the performance in vision processing, we separate the structure estimation and motion estimation. The structure estimation tracks the features which are the part of helmet model structure in the scene and the motion estimation filter estimates the position and orientation of the helmet. This algorithm is tested with using synthetic and real data. And the results show that the result of sensor fusion is successful.
Numerical Comparisons Between URANS and Hybrid RANS/LES at a High Reynolds Number Flow Using Unstructured Meshes
You, Ju-Yeol ; Kwon, Oh-Joon ;
International Journal of Aeronautical and Space Sciences, volume 11, issue 1, 2010, Pages 41~48
DOI : 10.5139/IJASS.2010.11.1.041
In the present study, the turbulent flow fields around a circular cylinder at
were investigated based on an unstructured mesh technique, and the comparisons between URANS(S-A, SST) and hybrid RANS/LES(DES, SAS) methods for the simulation of high Reynolds number flow have been conducted. For this purpose, unsteady characteristics of vortex shedding and time-averaged quantities were compared. A quasi-steady solution-adaptive mesh refinement was also made for the URANS and hybrid RANS/LES approaches. The results showed that the simple changes in the turbulent length scale or source term of turbulent models made the flow fields less dissipative and more realistic in hybrid RANS/LES methods than the URANS approaches.
Shock Response Prediction of a Low Altitude Earth Observation Satellite During Launch Vehicle Separation
Lee, Dae-Oen ; Han, Jae-Hung ; Jang, Hae-Won ; Woo, Sung-Hyun ; Kim, Kyung-Won ;
International Journal of Aeronautical and Space Sciences, volume 11, issue 1, 2010, Pages 49~57
DOI : 10.5139/IJASS.2010.11.1.049
Several pyrotechnic devices are employed over the course of satellite's missions, generally for the separation of structural subsystems and deployment of appendages. Firing of pyrotechnic devices results in impulsive loads characterized by high peak acceleration and high frequency content which can cause failures of various flight hardware elements and small components. Thus, accurate prediction of acceleration level in various components of spacecraft due to pyrotechnic devices is important. In this paper, two methods for pyroshock prediction, an empirical model and statistical energy analysis in conjunction with virtual mode synthesis, are applied to predict shock response of a low altitude earth observation satellite during launch vehicle separation. The predicted results are then evaluated through comparison with the shock test results.